Definitely No foul.
When officiating holding, first determine who has better feet. We don't really care where/how he is "grabbed". We call holding, not grabbing. In this play, the defender takes himself out of the play by going inside. A68 just walls him off. There is no material restriction whatsoever on the B player. B player did not "beat the feet" of A68. A68 just took him where he wants to go.
This official probably saw "hands outside" and called holding.